Windshield wiping mechanism



Nov. 17, 1942'. c. 1. MacNEIL 2,302,232

WINDSHIELD WIPING MECHANI SM Filed April 18, 1941 ClzarLasLil/Iac Patented Nov. 17, 1942 lTED STATES PATENT. OFFICE WINDSHIELD WIPING MECHANISM Charles}. MacNeil, Glen Ridgc,.N. J., assignor to BendixAviation Corporation, South Bend, Ind, a corporation of Delaware Application April 18, 1941, Serial No. 389,243

2 Claims. (on. 15-253) This invention relates to windshield wiping or other servo-mechanism, and particularly to the control 01 the stroke of such a mechanism.

An object of the invention; is to provide a servo-motor of novel construction for the actuation of a windshield wiper blade, a machine tool feed, or any equivalent part to be moved over a. limited range or movement.

Another object is to provide for control of the range of movement in such manner as to produce automatic variation in the length of the.

work stroke, according to conditions encountered. These and other objects of the invention will become apparent from inspection of the following specification when read with reference to the accompanying drawing wherein is illustrated the preferred embodiment of the invention. It is to be expressly understood, however, that the drawing is for the purpose or illustration only, and is not designed as a definition of the limits of the invention, reference being bad to the appended claims for this purpose.

In the drawing,

of snap-action mechanism it, this increase in pressure acting upon bellows ii will cause the latter to shift the valve It to the right, reversing the direction of the wiper. Any obstacle encountered in the reverse travel, will, of course, produce a corresponding reversing action.

This action will permit the blade to wipe either the entire windshield or a smaller section thereof free of ice; the stroke variation depending upon the setting of the spring l0, and the varying magnitude of the obstructing resistance or the ice or other obstacle in the blade's path. When no resistance is encountered (as in warm weather) the piston will, of course, traverse its complete stroke, after which the pressure rise (due to the resistance of the cylinder end wall) will reverse the valve position, as indicated above, to continue the-cycle. Y

It will be seen that the snap-action mechanism tends to accelerate the final stage of the shifting movement of the valve in each direction, and by 7 so doing there is assured a more rapid oscillation Figs. 1 and 3 show the relative positions of the parts constituting the preferred embodiment of the invention, Fig. 1 showing them at one extreme limit oi. valve movement, and Fig. 3 showing them at the other extreme.

P13. 2 shows the relationship as the valve passes the central point in its rightward or leftward travel. w

The invention is shown as embodied in apparatus including a power cylinder "I adapted to receive motive fluid at opposite ends, alternately, to reciprocate a piston 2 whose projecting rod 3 is linked to a wiper blade 5 (or other work part) through suitable linkage shown partly at The flow of motive fluid to cylinder I is by way of pump '6, manual valve 1, conduit 8, contalning a flow-restricting orifice 9, and a pressure-responsive valve i2; said valve I: being an important part of this invention. Motive fluid enters the valve I! (it may be hydraulic fluid or air) through orifice 9, and (with the valve ii in the position shown in Fig. 1) the fluid enters the cylinder through passage l3, to move piston! to the left. The blade will then move correspon, until it reaches the end of its stroke, or until it meets an obstacle (such as heavy ice on the windshield). If the latter is too resistant. it will stop the advance, and will cause a rise in the pressure of the fluid because of the reduced flow through orifice 9.

Depending upon the setting of the spring tension or the wiper blade. It will also be noted that the central portions of each valve bead (22, 23 and 24) are of slightly less extent than the diameter of the inlet and outlet ports, wherefore there is no complete cutting oil of fluid circulation at any point in the valve travel; the only mode of cut-oil being by turning the manual valve to the cut-off position. In the cut-oil position the manual valve diverts flow back to the sump, thus short-circuiting the cylinder I.

Communication is established between the bellows II .and the passage ill by the provision of a pipe as shown at It, which extends from the passage l3 to one end of the bellows Ii. At the end of the cylinder i opposite to the location of the passage 13 there is another passage it adapted to communicate with the bellows 2| by way of a pipe i6 extending from the passage it to the valve chamber to the source 20 and constitute means whereby fluid discharged from either end of the cylinder i, by way of either the discharge passage i3 or the discharge passage it, may re turn to the source 20; the discharge pipe i8 having communication with the passage it, by way of the valve chamber, when the valve is in the position indicated in Fig. 1, and the discharge pipe i9 having communication with the passage l3, by way of the valve. chamber, when the valve is in the position indicated in Fig. 3.

What is claimed is:

' 1. In a windshield cleaner of the type having a blade shiftable by a reciprocable piston, the combination with said reciprocable piston of means including a valve having a beaded portion shiftable first to one side and then the other of a single fluid inlet port, to supply fluid first to one side and then to the other side of said piston,

ing means comprising bellows connected to saidvalve at opposite ends thereof, and means for delivering fluid first to one and then to the other of said bellows, said fluid delivering means including conduits which alternately communicate with said fluid inlet port by way of said valve.

2. In a windshield cleaner of the type having a blade shiftable by a reciprocable piston, the combination with said reciprocable piston of means including a valve having a beaded portion shiftabl first to one side and then the other of a single fluid inlet port, to supply fluid first to one side and then to the other side of said piston, flexible pressure responsive means for reversing the direction of movement of said valve, said reversing means being operable at different points in successive, oppositely directed piston strokes, which different points correspond to the variations in the amount of resistance encountered by the shiitable blade as it proceeds in opposite directions from one stroke to another, said reversing means comprising bellows connected to said valve at opposit ends thereof, and means for delivering fluid first to one and then to the other of said bellows at pressure which increases as the advance of the piston, in either direction, is resisted, said fluid delivering means including conduits which alternately communicate with said fluid inlet port by way of said valve.

CHARLES I. MACNEIL. 

